Marvelous, that indeed does the trick. However, if the polynomial is of a higher order (see below) I again run into trouble.
For instance, if I want to find the real root of 0.1 + 0.5 (1-x)^4 - (1/y)=0, (which you can easily solve for x=1- [ 2 (1-0.1 y ) / y ]^(1/4) ), I again use
sol =...